fix: Always output release notes to stdout

Issue #65: #65

src/git_changelog/cli.py

@@ -643,7 +643,7 @@ def output_release_notes(
     input_file: str = "CHANGELOG.md",
     version_regex: str = DEFAULT_VERSION_REGEX,
     marker_line: str = DEFAULT_MARKER_LINE,
-    output_file: str | TextIO = sys.stdout,
+    output_file: str | TextIO | None = None,
 ) -> None:
     """Print release notes from existing changelog.
 
@@ -655,6 +655,7 @@ def output_release_notes(
         marker_line: The insertion marker line in the changelog.
         output_file: Where to print/write the release notes.
     """
+    output_file = output_file or sys.stdout
     release_notes = get_release_notes(input_file, version_regex, marker_line)
     try:
         output_file.write(release_notes)  # type: ignore[union-attr]
@@ -681,7 +682,7 @@ def main(args: list[str] | None = None) -> int:
             input_file=settings["input"],
             version_regex=settings["version_regex"],
             marker_line=settings["marker_line"],
-            output_file=settings["output"],
+            output_file=None,  # force writing to stdout
         )
         return 0